Process for polymerizing conjugated dienes

ABSTRACT

CONJUGATED DIENES ARE POLYMERIZED BY A NEW CATALYST SYSTEM WHICH PERMITS CONTROL OF THE MOLECULAR WEIGHT AND GIVES A MORE EASILY PROCESSED PRODUCT. THIS CATALYST SYSTEM COMPRISES (1) A SODIUM HYDROCARBON COMPOUND HAVING 1-10 CARBON ATOMS IN WHICH THE HYDROCARBON PORTION IS A PRIMARY, SECONDARY OR TERTIARY ALKYL RADICAL, AND (2) A POTASSIUM TERTIARY ALKOXIDE OF 4-10 CARBON ATOMS. THE DIENE POLYMERS PRODUCED BY THIS PROCESS HAVE CONTROLLABLE MOLECULAR WEIGHTS IN THE RANGE OF 25,000 TO 1,000,000, PREFERABLY 100,000-500,000, BROAD MOLECULAR WEIGHT DISTRIBUTION, GLASS TRANSITION TEMPERATURES HIGHER THAN NORMALLY OBTAINED, HIGH DEGREE OF BRANCHING AND ARE MORE EASILY PROCESSED IN THE PRODUCTION OF RUBBER AND OTHER COMPOSITIONS FOR COMMERCIAL USE.

United States Patent 3,775,392 PROCESS FOR POLYMERIZING CONJUGATEDDIENES Tai Chun Cheng, Mogadore, and Adel F. Halasa, Bath,

Ohio, assignors to The Firestone Tire & Rubber Company, Akron, Ohio NoDrawing. Continuation-impart of application Ser. No. 854,272, Aug. 29,1969. This application Sept. 7, 1971, Ser. No. 178,490

Int. Cl. C0811 1/20, 3/04, 3/06 US. Cl. 260-942 T 17 Claims ABSTRACT OFTHE DISCLOSURE Conjugated dienes are polymerized by a new catalystsystem which permits control of the molecular weight and gives a moreeasily processed product. This catalyst system comprises 1) a sodiumhydrocarbon compound having 1-10 carbon atoms in which the hydrocarbonportion is a primary, secondary or tertiary alkyl radical, and (2) apotassium tertiary alkoxide of 4-10 carbon atoms. The diene polymersproduced by this process have controllable molecular weights in therange of 25,000 to 1,000,000, preferably 100,000-500,000, broadmolecular weight distribution, glass transition temperatures higherthannormally obtained, high degree of branching and are more easilyprocessed in the production of rubber and other compositions forcommercial use.

This application is a continuation-in-part of application Ser. No.854,272, filed Aug. 29, 1969, now abandoned.

BACKGROUND OF THE INVENTION Field of the invention This inventionrelates to a process for the polymerization of dienes using a catalystcomposition comprising a sodium hydrocarbon compound and a potassiumalkoxide.

Related prior art The polymerization of conjugated dienes can beeffected in a variety of methods. However, there are variousdisadvantages in the various methods presently known includingundesirable or uncontrollable properties in the products, such as lackof control of molecular weight, molecular weight distribution andprocessability of the polymers. For example, the so-called Alfincatalyst system which has been studied extensively producespolybutadienes of approximately 5,000,000 molecular weight, or evenhigher, which are difiicult to process for commercial use. This catalystsystem generally comprises allyl sodium, sodium isopropoxide and sodiumchloride. There are a number of literature references describing theAlfin process, typical of which is the review article in Rubber Age,vol. 94, October 1963, pp. 87-92.

This Alfin catalyst system effects very rapid formation of a very highmolecular weight polymer having molecular weights of about 5,000,000with about 75% of the polymer in the trans-1,4 configuration. Incontrast, the polymerization by an alkyl sodium, such as amyl sodium,produces a much slower polymerization reaction to give a polymer havingas high as 70% in the 1,2 configuration but with a molecular weight toolow for the desired properties.

Polybutadienes prepared by the use of n-butyl lithium in n-hexane haveabout 8-10% 1,2; 53-54% trans-1,4 and 35-37% cis-1,4 configurations,which polymers do not have enough 1,2 configuration for the desiredproperties. By using polar modifiers or solvents, such as ethers,amines, etc., the vinyl content can be increased to up to 50-70%.However, the molecular weight distribution in ice such cases is sonarrow as to give poor processability. Moreover, the polar modifiers actas chain terminators and prevent active polymer products that might becoupled or otherwise post-treated to improve processability.Processability is very important for commercial rubber tire production.Among other disadvantages poor processability results in poor adhesionto fillers and thereby gives poor reinforcement.

High glass transition temperatures in butadiene polymers generallyindicate and accompany good wet traction. Butadiene emulsion polymershave low glass transition temperatures and have poor wet traction whenfabricated into tires.

SUMMARY OF THE INVENTION In accordance with the present invention, ithas now been found that conjugated diene polymers of controllablemolecular weight, broad molecular weight distribution, goodprocessability, high glass transition temperatures and good wet tractionare produced by the use of a catalyst system comprising the combinationof (1) a sodium alkyl, and (2) a potassium tertiary alkoxide. A thirdcomponent, namely a sodium halide, can be present in the catalyst systemdepending on the method used in preparing the sodium alkyl.

The hydrocarbon portion of the sodium hydrocarbon component has 1-10carbon atoms, and even though larger groups can be used, there is noparticular advantage. The hydrocarbon portion is alkyl, and the sodiumcan be attached to a primary, secondary or tertiary carbon atom.

These can be prepared by the reaction of metallic sodium with thecorresponding halohydrocarbon. In cases where it is desired to preparethe sodium hydrocarbon free of the byproduct sodium halide, this can bedone by adding a solution of sodium alkoxide, such as NaOt-Bu incyclohexane, to a hexane solution of halide-free alkyl lithium. Theresultant Na lkyl precipitates and, after filtering, the solid Na alkylis washed under nitrogen with hexane to remove any lithium residues.

In addition to monosodium alkyl compounds, hydrocarbons having twosodium atoms attached can also be used, such as butane-l,4-disodium,pentane-l,4-disodium, etc. These compounds are prepared by the samemethods as described above for preparing the monosodium compoundsstarting With dichloroalkanes or dilithioalkanes. However thesecompounds are not as practical as the monosodium compounds and thelatter are therefore preferred. Nevertheless, the use of the disodiumhydrocarbon compounds are considered as coming Within the scope of thisinvention.

In the potassium alkoxide, it is important that the alkoxide is atertiary alkoxide. The hydrocarbon portion of this alkoxideadvantageously has 4-10 carbon atoms. While even larger groups can beused, there is no added advantage, and the resultant compounds are moresluggish in their activity.

The potassium alkoxide is prepared by the reaction of metallic potassiumwith a tertiary alcohol. This is ad vantageously prepared separately andexcess potassium is used to insure that no unreacted alcohol remains toreact with the sodium or sodium hydrocarbon upon mixture of activitysince there will be at least a portion of the sodium hydrocarbonassociated with two moles of the alkoxide. Consequently, it is desirableto keep within the range of 1.5-2.5 moles of potassium alkoxide per moleof sodium hydrocarbon.

If a sodium halide is present, it is generally in the amount depositedby the reaction of sodium with the halohydrocarbon by which the sodiumhydrocarbon is formed, so that generally there is a mole of sodiumhalide per mole of sodium hydrocarbon. The halide is generally thechloride or bromide, since these are more economical than the fluorideand iodide.

The catalyst can be prepared at room temperature, but preferably at C.or even lower.

The effectiveness of the tertiary alkoxide as an active component in thepresent catalyst system is surprising, particularly in view of theteaching against the use of tertiary alkoxides in the Alfin catalystsystem as reported in the last paragrauph on page 637 of Robert W. Lenzsbook on Organic Chemistry of Synthetic High Polymers, IntersciencePublishers, New York (1969), where it is stated, in a discussion ofAlfin catalyst systems, Inactive catalysts are formed with alkoxides ofn-propanol, t-

pentanol, allyl alcohol and other non-secondary alcohols,

. (Underscoring added.)

Typical sodium hydrocarbon compounds that can be used include compoundsin which the hydrocarbon portion is methyl, ethyl, n-propyl, isopropyl,n-butyl, secbutyl, t-butyl, n-amyl, sec.-amyl, t-amyl, n-hexyl, sec.-hexyl, t-hexyl, n-octyl, 1,1,5-trimethyl-pentyl, n-decyl, 1-methyl-2,4-diethyl-pentyl, phenyl, tolyl, ethylphenyl, naphthyl,methylnaphthyl, benzyl, phenethyl, etc.

Typical potassium tertiary alkoxides that are suitable include those inwhich the hydrocarbon portions are tbutyl, t-amyl (or1,1-dimethyl-propyl), 1,1,4-trimethylpentyl,l-methyl-1,4-diethyl-pentyl, l-methyl-l-phenyl propyl, etc.

The catalyst is used in a proportion of 0.1 to 2 millimoles per 100grams of monomer. The polymerization temperature is advantageously nohigher than 40 C., and is preferably no higher than 30 C. While highertemperatures can be used, even as high as 70 C., the yield and molecularweight decrease when temperatures exceed 40 C.

Polybutadienes-produced at temperatures of 40 C. or lower have molecularweights as high as 1,000,000, generally 100,000 to 500,00. Yields ashigh as 98-99% are easily produced. The 1,2-configuration in the polymeris at least 35% and generally in the range of 35 to 50%. I has beenfound that desirable wet traction or skid resistance properties requireat least 35% 1,2 configuration in the polymers. In contrastcorresponding emulsion polymers, which have low glass transitiontemperatures (55 to 59 C.), also have poor wet traction properties.These polymers have -25% 1,2 configuration and 75-80% trans-1,4.

The polymerization is advantageously effected in the presence of aninert diluent to facilitate handling of the polymer and to give bettertemperature control. Normally liquid hydrocarbons are preferred for thispurpose, such as benzene, toluene, saturated aliphatic hydrocarbonspreferably of the straight chain variety, such as n-hexane, n-heptane,etc. However, where provision is made for external heat dissipation andtemperature control, the

solvent can be omitted.

tion include: 1,3-butadiene, isoprene, chloroprene, 2-phenyl-1,3-butadiene, piperylene, etc.

Although butadiene homopolymers are preferred in the practice of thisinvention, butadiene copolymers can also be used where the comonomersimpart desirable properties and do not detract from the polymerproperties. The comonomers are preferably olefins, such as butene-l, nbutene-Z, isobutylene, n-pentene-l, n-pentene-Z and the like, and alsoincluding vinyl aryl or isopropenyl aryl compounds or derivativesthereof having alkyl, aralkyl, cycloalkyl or chlorine attached to thearomatic nucleus, and preferably having no more than 20 carbon atoms.Typical of these aromatic comonomers are styrene, alphamethyl styrene,vinyl toluene, isopropenyl toluene, ethyl styrene, p-cyclohexyl styrene,0-, mand p-Cl-styrene, vinyl naphthalene, vinyl cyclohexyl naphthalene,vinyl methyl naphthalene, vinyl butyl naphthalene, isopropenylnaphthalene, isopropenyl isopropyl naphthalene, l-vinyl-4-chloronaphthalene, l isopropenyl-5-chloronaphthalene, vinyl diphenyl,vinyl diphenylethane, 4-vinyl-4'-methyldiphenyl,4-vinyl-4-chlorodiphenyl, and the like. Preferably such comonomers haveno more than 12 carbon atoms. Where such comonomers are to be used,generally at least 1%, preferably at least 5% by weight should be usedand as much as 60%, preferably no more than 30% may be used.

In referring above to millimoles of catalyst this corresponds to themillimoles of sodium hydrocarbon since the catalyst is regarded or atleast calculated as a complex of the potassium alkoxide and the sodiumhydrocarbon.

SPECIFIC EMBODIMENTS OF INVENTION The investion is illustrated by thefollowing examples which are intended merely for purpose of illustrationand are not to be regarded as limiting the scope of the invention or themanner in which it may be practiced. Unless specifically indicatedotherwise, parts and percentages are given by weight.

EXAMPLE I To a 3-necked flask which is equipped with a high speed airstirrer, a nitrogen gas inlet, a Dry Ice reflux condenser and anexternal bath (maintained at -10 C.), there is added 800 ml. of dryhexane and then 53 m1. of a 40% dispersion of sodium in mineral oil(containing 20.6 gm. of metallic sodium). This slurry is cooled to --10C. and 38.9 gm. of dry n-butyl chloride is added slowly with high speedagitation. After the addition of the n-butyl chloride, the reactionmixture is stirred continuously for about 60 minutes. At the end of thistime 89.6 gm. of potassium t-butoxide is added. The resultant mixture isstirred for an additional 30 minutes at -10 C. then the temperature israised gradually to room temperature and the slurry is transferred to abottle in which a nitrogen atmosphere is maintained while the mixture isallowed to age for 1-2 weeks.

EXAMPLE II By reversing the order of addition of the reagents in ExampleI it is possible to avoid the aging period required in Example I, andthus permit the use of the catalyst system immediately upon preparation.This is done by adding the 89.6 gm. of potassium t-butoxide to thesuspension of sodium-mineral oil-hexane prior to the addition of then-butyl chloride. After the KOtBu is added, the mixture is stirred andthen the n-butyl chloride added gradually with the stirring continuedfor about 60 minutes after the n-butyl chloride addition is completed.The catalyst is then ready for use without any aging.

EXAMPLE III To a moisture-free reactor which has been flushed with drynitrogen, there is added 1,584 gms. of a hexane solution containing365.9 gms. of butadiene. The solution is stirred for about 10 minutes at30 C. and 5.592 millimoles of catalyst prepared as described in ExampleI or Example 11 is added with a hypodermic syringe under 50 lbs. ofnitrogen pressure at 30 C. The system is immediately closed and thereactor rotated in a polymeriza- Cyclix B. This is cured for 30 minutesat 300 F. and gives the following test results:

Comtion bath maintained at 30 C. After about 4 hours, a 5 me res: Nereddish polymer is obained. This is collected by pouring W p m themixture into a large amount of methanol and 20 ml. ggggg g t gg Skidresistanwindw 100 100 of anantioxidant, su as p-p y The p v- Surface 1goiaeIIII IIIIIIIIIIIIIZI 91 11a mer is dried and a polymer yield of365.3 gins. or 98% 89 109 of theoretical is obtained. The molecularweight of the .l fi?3{;if 3f;f*9 polymer is approximately 500,000.

EXAMPLE VI EXAMPLE IV The procedures of Example I-III are repeated withTh procedure of E l 111 i repeated a number similar results usingequivalent amounts of other sodium 15 11 1 df 11111 alklhlid' of timesusing 1n one case an Alfin catalyst prepared a Y as P p Yomt e 0 W1I1gya according to the procedure described by Hansley and (a) B 1 iGreenberg 1n Rubber Journal, 146, 42 (1964), and in (b) t amy1fluorideother cases the procedure of Example III is repeated (e) zehloromwemane1dent1cally, m one case using the same temperature-- (d) z hl z s dithylh namely 30 C.-and mother cases using temperatures of (e) 2-iodo nhexane 50 and 70 C. respectively. Other cond tions and results (f)1,4dieh1ombutane are tabulated below in Table I. As will be noted, themolecular weight of the Alfin-catalyzed polymer, as indi- EXAMPLE VII bythe g dllllte Solutlon vlscosity is much The procedures of ExamplesI-III are repeated with hlghel' than the P Y Produced Wlth the catalystsimilar results using in place of the potassium t-butoxide system ofthis invention. It W111 also be noted that, where equivalent weightsrespectively as the Alfin catalyst produces a polymer having 20% (a) P tt l 1,2 configuration, the polymers produced by the catalyst ,2323% 5:3(fimeth lhexane system of this invention range from 37.8% to 47.7% of Pt th y y this configuration. It will also be noted that the higher (c) oassmm exoxl e temperatures cause a reduction in the molecular weightEXAMPLE VIII as evldenc-ed by the DISV and the pare-em of more Theprocedure of Examples I-III are repeated a number structure is reducedsomewhat. The y1elds are also reof times usmg in place of the butadienean equivalent duced at the higher temperatures, and, therefore, it ISweight res ecfivel of generally desirable to use temperatures no higherthan p y about 40 C. a) Isoprene (b) Chloroprene TABLE I mMole I.R.,percent catalyst] Temp 60 Percent Cis- Trans- Catalyst C. monomer D Vgel 1,4 ,4 1,2

(c) Piperylene EXAMPLE (d) 2-phenyl:1,3-butad1ene V 50 (e) 75-25 mixtureof butadiene and styrene Comparative tests are made on a polybut-adienepre- (f) 70'30 mtxmre of-butadlFm and vmyl toluene pared according toExample III and a butyl lithium cat- Wz g g fP alyzed polybutadiene of atype bemg used commercially 75 m l u a 16116 3 i for tire production.The polymer produced accordlng to 1) m e 0 lsoprene an exene' thisinvention shows a bulk viscosity almost three times Th r s lt a similar.as high as the commercial type butyl lithium-catalyzed polybutadiene.However the new polymer shows only EXAMPLE IX slightly higher inherentviscosity measurements than for The procedures of Examples I-III arerepeated with the commercial type. This information together with thesimilar results using in place of the hexane an equivalent respectivemolecular weight distribution determinations amount respectively of:benzene, toluene, n-octane, cycloshows that the polymers of thisinvention are highly hexane and methylcyclohexanc. branched. Moreoverthe overall processability characteristics of this polymer are betterthan the corresponding EXAMPLE X characteristics of the comparedcommercial type. When The Procedures of Examples I and H f p d 118mg therespective polymers are blended respectively in a an equal amount ofdrydrethyl ether in place of the nstandard 011 recipe and tested withstandard laboratory hexane. After the final stirring is completed anlcalthe sch traction devices the new polymer of this invention tion allowedto come to room temperature, t e precipiregisters about 51% improvementover the commercial tated sodium chloride is removed from the ethersolution type on the medium andhigh coefficient of friction surbyfiltration. Then 800 m1. of dry benzene is added and faces. Thecomposition with the new polymer has a faster the ether removed bygradual and careful application of cure rate which results in a slightlyhigher modulus and reduced pressure. The ether is recovered in a Dry Icetensile strength and a lower running temperature than the trap. When theinitial amount of ether has been recovered, commercial type. The recipeused for the testing comthe distillation is stopped. The resultantcatalyst suspenposition is: 100 (parts) polymer; 70 ISAF Black; 43 oil;sions are used with similar results 1n the procedures 2.5 ZnO; 2.0stearic acid; 1.0 Santoflex 13; 1.7 sulfur; 1.4

of Examples III, VI, VII and VIII.

7 EXAMPLE XI The procedures of Examples I, II and III are repeated twiceeach, using in one series of the respective procedures potassiumn-butoxide, and in the other series potassium sec.-butoxide in place ofthe tertiary butoxide. The resultant polymerizations are veryineffective giving low conversions (less than 40%) and low molecularweight products (less than 10,000).

EXAMPLE XII A catalyst system free of halide is prepared as follows: To600 ml. of a hexane solution containing one mole of halide-free n-BuLithere is added with stirring and under a nitrogen atmosphere 600 ml. ofa cyclohexane solution containing one mole of Na t-amyloxide. The n-BuNaprecipitate is filtered and washed under nitrogen several times withcyclohexane. This material upon analysis shows less than 1.44% Li beingpresent.

A number of 28 oz. polymerization bottles are charged, after beingflushed with nitrogen, with 60 gm. of butadiene in 260 gm. of hexanesolution. The bottles are sealed with caps having an opening covered bya rubber liner covered on the inside with aluminum foil, and the bottleand its contents brought to a temperature of 30 C. Using the halide-freen-BuNa prepared as described above, or n-amyl Na similarly prepared, orthe salt-containing Na alkyl as specified and prepared according toExample II, the respective catalyst combinations described below areinjected as a hexane solution by a hypodermic syring inserted throughthe rubber liner in the sealing cap of the bottle. The bottles areplaced in a polymerization bath maintained at 30 C. and rotated for fourhours. (The specified metal alkoxides are available haildefreecommercially or may be prepared by addition of the stoichiometric amountof the appropriate alcohol to a mineral oil suspension of the finelydivided metal.) The results are tabulated below in Tables II-III.

TABLE II Milllmole per 60 g. of monomer (butadlene) n-Bu n-Bu Na, Na,salt-tree with salt Percent conv.

KOtArn Mol wt.

TABLE III Millimoles per 60 g. of monomer (butadiene) n-Am Na, with saltPercent conv.

KOn-Bu M01 wt.

EXAMPLE XIII mMoles NnOt-AM/ NaOt-Bu/ 60 g. 60 g. Na n-Bu, Na n-Bu,Percent monomer monomer salt-free with salt Mol. wt. conv;

The dilute solution viscosity (DSV) referred to above is defined as theinherent viscosity determined at 25 C. on a 0.4% solution of the polymerin toluene. It is calculated by dividing the natural logarithm of therelative viscosity by the percent concentration of the solution, i.e.,it is the inherent viscosity measured at 0.4% concentration. Themolecular weights reported herein are determined from these viscosities.

While certain features of this invention have been described in detailwith respect to various embodiments thereof, it will, of course, beapparent that other modifications can be made within the spirit andscope of this invention and it is not intended to limit the invention tothe exact details shown above except insofar as they are defined in thefollowing claims.

The invention claimed is:

1. A process for the hydrocarbon solution polymerization of a monmercomposition containing at least 70 percent conjugated diene to a polymerhaving a molecular weight about 25,000 to 1,000,000 and having at least35 percent of the butadiene therein in the 1,2-configuration comprisingthe steps of maintaining said monomer composition at a temperature of nomore than 70 C. in intimate contact with a catalyst compositionconsisting essentially of:

(a) a sodium hydrocarbon having 110 carbon atoms therein selected fromthe class consisting of sodium alkyls; and

(b) a potassium tertiary alkoxide of no more than 10 carbon atoms,

the concentration of said catalyst composition being 0.1- 2 millimolesof catalyst per grams of said monomer composition, and said potassiumalkoxide being present in said catalyst composition in a ratio of1.5-2.5 moles per mole of sodium hydrocarbon, said polymerization beingconducted for a period of at least one hour.

2. The process of claim 1 in which said temperature is no more than 30C.

3. The process of claim 2 in which said conjugated diene is1,3-butadiene.

4. The process of claim 2 in which said monomer composition isessentially all 1,3-butadiene.

5. The process of claim 4 in which said sodium hydrocarbon is sodiumn-butyl.

6. The process of claim 4 in which said polymerization is conducted forat least 10 hours.

7. The process of claim 4 in which said potassium alkoxide is potassiumtertiray-butoxide.

8. The process of claim 7 in which said sodium hydrocarbon is sodiumn-butyl.

9. The process of claim 8 in which said ratio of potassium alkoxide tosodium hydrocarbon is approximately two.

10. The process of claim 9 in which said polymerization is conducted inn-hexane solution.

11. The process of claim 10 in which said monomer is in n-hexanesolution at a concentration of 10-25 percent by weight.

12. The process of claim 1 in which said catalyst composition is presentat a concentration of 0.3-1.0 millimoles per 100 grams of said monomer.

13. The process of claim 1 in which said monomer composition isdissolved in a liquid hydrocarbon having a boiling point no higher thanC.

14. The process of claim 13 in which said monomer composition is presentat a concentration of 10-25 percent by weight.

15. The process of claim 14 in which said liquid hydrocarbon isn-hexane.

16. The process of claim 1 in which said monomer composition comprises7095% by weight of 1,3-butadiene and 5-30% by weight of styrene.

17. The process of claim 16 in which said alkoxide is a potassiumtertiary-alkoxide.

(References on following page) 9 10 References Cited OTHER REFERENCESUNITED STATES PATENTS Alfin Catalysts" by Morton, Encyclopedia ofPolymer 3 2 5 80 8 19 Fol-man et l 2 0 942 Science and Technology, pp.629-637, Interscience.

{Z322 3322 Q 3 5; 5 JAMES A. SEIDLECK, Primary Examiner 3,324,191 6/1967 Wofford: 260669 W. F. HAMROCK, Assistant Examiner 3,331,821 7/1967Strobel- 26083.7 3,380,984 4/1968 Birchall et a1. 26094.2

FOREIGN PATENTS b 26085.3 R, 94.2 T; 252431 R 782,970 1957 Great Britain26094.2

ggggy UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Pa n5.775.592 Dated November 212, 1212i Inv nt m (11mm Chang and Ads] FarhanHs'lasa It is certified that error appears in the above-identifiedpatent and that said Letters Patent are hereby corrected as shown below:

I" v r "'1 In Column 2, Line asfnk l" should be --alkyl--.

In Column 5, Line 19, "paragrauph" should be peragraph--. In Column 5Line +9, '1" should be --It--.

In Column 7, Line 55, "hailde-" should be -'-halide- In Column 8, Line48 (Claim 7) "tertiray" should be --tertiaI'y--.,

Signed and, vsealed this Lpth day of 7 June 197) (SEAL) Attest:

EDWARD I LF'LE'I'CHER, JR. C I IARSHALL DANN Attesting Officer'Commissioner of- Patents

